Historically, the treatment of water and other substances has required the consumption of energy and has been an expensive process. Wastewater is generated from numerous industrial processes. In particular, food and beverage and agricultural processes generate a substantial volume of wastewater. In addition, many methods of obtaining fuel for energy result in environmental hazards such as, for example, polluted groundwater. Most waste treatment processes involve the oxidation or reduction of the target pollutant.
Bio-electrochemical systems (BESs) are a class of technologies capable of treating water while generating electricity or other value-added products such as methane and hydrogen. Based on the ability of newly discovered microbes (termed “electricigens”) to interact electrically with electrodes through direct electrode contact, soluble mediators, and conductive biological nanowires, BESs can be configured into fuel cells with living, regenerative catalysts.
Bio-electrochemical systems utilize biology as the catalytic system for an oxidation or reduction reaction. Bio-electrochemical system applications can feature either or both electrode reactions and include, amongst others, processes for waste treatment, chemical formation, and energy production. The biological component of a bio-electrochemical system interfaces with an electrode which serves as the interface to the electrical circuitry coupling the two (oxidation and reduction) half-cell reactions. As such, the properties of the electrodes of a bio-electrochemical system are critical to the operation of the system. The electrodes should provide, at a minimum, high electrical conductivity, large surface area, and bio-compatible material.